In recent years, the developing period of an automobile tends to be more and more shortened. In accordance with this tendency, the developing period of an electric mounting device mounted to the automobile also tends to be shortened. Many techniques for simulating the electric wiring including the load part, the electric wire, a switching device and the electric power source are proposed from such a present situation. For example, JP-A-2002-24314 shows a device in which plural electric parts are selectively arranged on an input screen, and names and formats of these electric parts are inputted and predetermined desirable electric wiring is performed, and protecting part fusion and wiring smoking at a short-circuiting time in this electric wiring are then simulated.
However, in accordance with the above relating simulator, the electric wiring at the short-circuiting time is evaluated, but no evaluation of the electric wiring at the normal time occupying a large portion of an operating time is particularly made. Further, in the evaluation of the electric wiring of the vehicle, its evaluation reference should be changed in accordance with a maker name of the vehicle mounting this electric wiring, the kind of the protecting part, an arranging place of the protecting part, or the kind of the vehicle mounting the electric wiring, and the state of a switching device. However, no consideration is taken until these points in the above relating simulator. Accordingly, a simulator able to accurately make such a characteristic evaluation of the electric wiring of the vehicle is eagerly desired.